This invention relates to a phase inverter circuit which is used as a video linear IC in a servo circuit or the like in a video disk player, for inverting a phase at a desired time instant.
One example of a conventional phase inverter circuit of this type is shown in FIG. 1. The phase inverter circuit includes a first differential current gate 1 made up of transistors 1a and 1b; a second differential current gate 2 made up of transistors 2a and 2b; a third differential current gate 3 made up of transistors 3a and 3b; a constant current source 4; input signal terminals 51 and 52; input terminals 61 and 62 through which a signal whose phase is to be inverted is received; output terminals 71 and 72; and load resistors 81 and 82.
FIG. 2 is a waveform diagram for describing the operation of the circuit shown in FIG. 1. When an input signal Sa as shown in FIG. 2(a) is applied across the input terminals 51 and 52 and an input signal Sb as shown in FIG. 2(b) is applied across the input terminals 61 and 62, an output voltage Vo as shown in FIG. 2(c) is developed across the output terminals 71 and 72.
As is apparent from the above description, the phase of the output voltage Vo is inverted in response to the high and low levels of the input signal Sb.
In the above-described conventional phase inverter circuit, the circuit elements are cascade-connected between the power source terminal Vcc and the ground GND. Therefore, it is necessary to employ a high power source in order to obtain an output voltage as required. This design is thus disadvantageous when it is required to provide the phase inverter circuit in the form of an integrated circuit.